[PATCH] drm/managed: Fix off-by-one in warning

[Daniel Vetter]

Ok 0day people uploaded the tree they tested (from patches) now, I
confirmed it's indeed this line that's blowing up.
-Daniel

On Sat, Mar 28, 2020 at 5:24 PM Daniel Vetter <daniel.vetter at ffwll.ch> wrote:
>
> I'm thinking this is the warning that fired in the 0day report, but I
> can't double-check yet since 0day didn't upload its source tree
> anywhere I can check. And all the drivers I can easily test don't use
> drm_dev_alloc anymore ...
>
> Also if I'm correct supreme amounts of bad luck because usually kslap
> (for bigger structures) gives us something quite a bit bigger than
> what we asked for.
>
> Reported-by: kernel test robot <lkp at intel.com>
> Fixes: c6603c740e0e ("drm: add managed resources tied to drm_device")
> Cc: Sam Ravnborg <sam at ravnborg.org>
> Cc: Thomas Zimmermann <tzimmermann at suse.de>
> Cc: Dan Carpenter <dan.carpenter at oracle.com>
> Cc: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> Cc: Neil Armstrong <narmstrong at baylibre.com
> Cc: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
> Cc: "Rafael J. Wysocki" <rafael at kernel.org>
> Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
> ---
>  drivers/gpu/drm/drm_managed.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_managed.c b/drivers/gpu/drm/drm_managed.c
> index 4955241ceb4c..9cebfe370a65 100644
> --- a/drivers/gpu/drm/drm_managed.c
> +++ b/drivers/gpu/drm/drm_managed.c
> @@ -139,8 +139,7 @@ void drmm_add_final_kfree(struct drm_device *dev, void *container)
>  {
>         WARN_ON(dev->managed.final_kfree);
>         WARN_ON(dev < (struct drm_device *) container);
> -       WARN_ON(dev + 1 >=
> -               (struct drm_device *) (container + ksize(container)));
> +       WARN_ON(dev + 1 > (struct drm_device *) (container + ksize(container)));
>         dev->managed.final_kfree = container;
>  }
>  EXPORT_SYMBOL(drmm_add_final_kfree);
> --
> 2.25.1
>


-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch